Gadolinium, Random, Urine

CPT CODE:

USEFUL FOR:

Diagnosis of nephrogenic systemic fibrosis (NSF) by documenting gadolinium excretion in excess of that typical for the time duration following exposure to contrast media

SPECIMEN REQUIRED:

1 mL from a random urine collection as follows:1.  Collect in a clean, plastic urine collection container(s) with     no metal cap(s) or glued insert(s).2.  Pour 1 mL into a plastic, 13-mL urine tube or a clean,      plastic aliquot container with no metal cap or glued insert.3.  See "Metals Analysis-Collection and Transport'' in Special      Instructions for complete instructions.4.  Send specimen refrigerated.

TRANSPORT TEMPERATURE:

Refrig\Frozen OK\Ambient OK

CLINICAL INFORMATION:

Gadolinium is a member of the lanthanide series of the periodic table of elements and is considered a nonessential element. Due to its paramagnetic properties, chelated gadolinium is commonly employed as contrast media for magnetic resonance imaging (MRI) and computer tomography (CT) scanning.(1)
Gadolinium is eliminated primarily by renal filtration. In healthy subjects with normal renal function, the plasma half-life of gadolinium is approximately 90 minutes.(1) Patients with reduced renal function exhibit an increased gadolinium excretion half-life.(2)
Gadolinium has been associated with the nephrogenic systemic fibrosis (NSF) in patients with impaired renal function.(2,3) In this syndrome, prolonged retention of gadolinium is thought to allow the gadolinium cation to dissociate from its synthetic organic chelator and deposit predominantly in the skin, although other organs may be affected as well. These patients are often severely debilitated by progressive skin thickening and tightening. Fibrosis of skeletal muscle, lungs, liver, testes, and myocardium have all been observed, often with fatal results. Because the ionic radius of gadolinium (3 ) is similar to that of calcium (2 ), it may also deposit in bone.(1)
Three hemodialysis treatments are required to substantially remove gadolinium from patients with impaired renal function; peritoneal dialysis is not effective.(4)

CLINICAL INTERPRETATION:

Elevated gadolinium (>0.5 mcg/L) observed in a random urine specimen collected >48 hours after administration of gadolinium-containing contrast media indicates impaired ability to eliminate gadolinium. These patients have an increased risk of developing NSF.
A normal value is <0.5 mcg/L; the lower limit of the assay's reportable range is 0.1 mcg/L.

REFERENCE VALUES:

<0.5 mcg/L